Two primary video format standards are utilized worldwide to record, transmit, and display composite video data, namely, the National Television Systems Committee (NTSC) and the Phase Alternating Line (PAL) standards. Both the NTSC and PAL standards define interlaced video systems in which one frame of display pixels is partitioned into alternating interlaced fields, with each interlaced field updated at twice the update rate of the frame. Additionally, many digital versatile disk (DVD) players, DVD player-recorders, and similar video recording and playback systems, output data in an interlaced format, depending on the format utilized during recording.
On the other hand, many state of the art display systems, such as high definition television (HDTV) sets, generate displays using a progressive scan format. In the progressive scan format, video data are transmitted and displayed in frames, which are not partitioned into fields. In other words, each display frame is generated by sequentially scanning through the lines of each frame at the original interlaced field update rate.
Hence, in order to interface an interlaced video source, such as an interlaced-output DVD player, with a progressive-scan display system, such as a HDTV set, deinterlacing must be performed. Several deinterlacing techniques exist for converting interlaced video into progressive scan video; however, each has significant drawbacks. For example, in the weaving technique, the lines of the current field are merged with the lines of the previous field to weave a full frame. The resulting frames are generated at the full update rate. Weaving, however, often creates feathering, which is similar to ghosting-like un-sharpness of moving display objects. In the bob technique, each field is converted to a full frame by interpolating between the available lines of that same field to generate the missing pixel lines. The interpolated frames are then displayed at the field update rate. The bob technique, however, often misses information representing high frequency detail. Motion compensated deinterlacing systems are also available which compensate for un-sharpness due to motion, but these systems are normally difficult and expensive to implement and are therefore mostly limited to high-end applications.
Given increasing popularity of progressive scan display systems, as well as the need to maintain compatibility with systems generating interlaced display data, new deinterlacing techniques are required. These techniques should minimize the generation of display artifacts, such as feathering, while at the same time being easier and less expensive to implement than those existing techniques. Additionally, such techniques should minimize the introduction of errors which often occur during the interpolation of pixel data.